Welcome to the Facepunch electronics thread, this thread is for anyone who has an interest in electronics, be it analog, digital or just blowing shit up in their free time.
If you have something you want to show or desire to get into electronics just make a post and someone will be along eventually.

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[tr][td]chipset[/td][/tr]
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[tr][td]Electric water pump timer[/td][td]Vacuum fluorescent display[/td][td]Guide to interfacing microcontrollers with high power devices[/td][/tr][/table]

Art of Electronics by Paul Horowitz and Winfield Hill
Without a doubt the most complete and informative book on electronics, although the
current 2nd edition is rather old (1989) it is still extremely relevant to modern electronics.
If you're going to buy any book this should be the one, although it is not designed for beginners.

Complete Digital Design by Mark Balch
An excellent book that covers all the basics such as boolean logic,
karnaugh maps, binary arithmetic and more advanced topics such as serial
communication, microprocessors and the practical design of digital circuits.

Principles of Electric Circuits by Thomas L. Floyd (9th ed)
A very good book for beginners that unlike most comes in an electron flow
version as well, if you prefer that. The book is full of well drawn diagrams and
helpful pictures which makes reading easy and fun, in addition at the end of each
chapter there is a quiz to make sure you fully understand what you have read.

Troubleshooting Analog Circuits by Robert A. Pease (Bob Pease)
An excellent book by an excellent author, this book contains a lot of useful
information that is invaluable if you are interested in getting into electronic
repair.

Power Electronics Handbook by Muhammad H. Rashid et al
A huge amount of information on power circuits and components
a must have if you're interested in power electronics.

http://www.allaboutcircuits.com/
A very informative e-book that can be read online or downloaded, it explains things
very nicely and with plenty of pictures and diagrams so it is suitable for beginners.
I highly recommend although the book is not complete.

http://www.eevblog.com/
Excellent video blog all about electronics, definitely worth watching.
Also has an excellent forum suitable both for beginners and professionals.

{Q} How much does it cost to get started with electronics ?{A} Not much, depending on how far you want to go anywhere from £30 to £200

{Q} What is the best way to learn electronics ?{A} Reading books is usually the best way, however if you can't stand reading there are plenty of alternative options, don't always assume what you're reading is correct however.

{Q} Where do I get an oscilloscope ?{A} Ebay is the best place for picking up a low cost analog scope, avoid PC based scopes and mini scopes like the DSO Nano, alternatively you can get a brand new digital scope from about £200.

Bitsbox - Small selection of components but very cheap shipping, £1.50 UK, £2.75 Europe, £4.00 anywhere else.RS - A well known supplier with large selection, shipping is fairly cheap but no Paypal.Farnell - Another excellent supplier with a very large selection, minimum order applies and no Paypal.DealExtreme - Sells a lot of made in china stuff but you can get some really good deals such as the Rigol DS1052E.Rapid - Decent selection but not the cheapest, shipping outside the UK is also fairly expensive.Maplin Electronics - Similar to rapid but even more expensive, not available outside the UK as far as I'm aware, avoid.Digikey - Excellent selection of components but fairly expensive shipping.Sure Electronics - Small selection but some good value for money component kits.Sparkfun Electronics - Nice selection with some good deals, still quite expensive.RSH Electronics - Small selection with some great bargain packs, cheap delivery £4.00 internationalTayda Electronics - Decent selection of cheap parts, direct from Thailand so expect some delay in delivery.

Working with electricity is generally quite safe, however here are a some useful tips that will help you avoid severe injury or in the worst case death.

Avoid working with mains electricity unless you are confident with what you're doing
Probe live circuits with your right hand and keep your left hand in your pocket
Keep your hands clean and dry
Do not wear any metal objects even around low voltage
Never go near high energy (3 phase) systems with a non-industry grade multimeter
Use a properly fused multimeter to avoid risk of explosion
Ensure high voltage capacitors are discharged before touching a circuit
Never make changes to household wiring unless you REALLY know what you're doing
NEVER EVER play around with microwave ovens they're potentially lethal

I need some help with multiplexing. Right now i have about 20 LEDs that need to be controlled separately. I have acces to a Arduno Uno (14 i/o ports + 6 analog ports that should be able to act as outputs), but there also are 5 inputs needed. I need the best way of multiplexing. This is supposed to be a traffic light, so the least flickering possible. I also have a supply of various resistors, capacitors (100 µF), transistors (BC 547 B). VistaPOWA explained multiplexing to me before, kind of know how it supposed to work but can't figure out how to actually make it work yet.

You could always look into charlieplexing the LEDs, though I don't know how you'd go about having all 6 traffic lights lit at the same time, switching between the 6 sets faster than the eye can see seems to be the most straightforward solution, and shouldn't be too hard. 20 charlieplexed LEDs should only take 5 pins, so that leaves you plenty of room for your inputs too.

Each pin connects to each other pin through two LEDs of opposite orientation in parallel.

So if you add a fourth pin, you would also add:
1->4 4->1
2->4 4->2
3->4 4->3

etc.

Then, you set all the pins to High-Z, except for the two that control the LED you want to light. If you set one HIGH and the other LOW, then one LED will light up. If you do the reverse, the other LED will light up.

A reserve price is a price a seller can set when they create an auction-style listing. It's the minimum price they're willing to accept for an item. If the bidding doesn't reach this price, they aren't obligated to sell the item.

Sellers might use a reserve price because it allows them to set a low starting price to generate interest and bidding, but protects them from having to sell their item at a price that they feel is too low.

The reserve price is hidden from buyers, but some sellers include it in the item description or tell buyers who contact them and ask what the reserve price is. However, sellers aren't obligated to reveal their reserve price.

Yeah, fuck Ebay if they actually condone this sort of thing. That's just dishonest.
Starting bids should always be the minimum amount a seller is willing to settle for. If it's not, then it has absolutely no meaning whatsoever, and it's a farce, not a proper auction.
At that point, there's no reason not to set your starting bid to $0.01 for every single item just to have it at the top of the list when sorted by price.

Also, I think everyone would know in an instant if a nuclear bomb exploded somewhere.

The point is to immediately cut the power to EMP-sensitive equipment before the EM-Pulse arrives at the equipment and destroys it. This is not meant to warn humans, although it can also be used for that.

3rd February 2012
Last edited by Chryseus; 3rd February 2012 at 09:42PM.
Post #36

Correct me if I'm wrong but I though you also had to shield something to protect it from an EMP.
Also if a bomb did go off, I doubt you'd want to be sitting around playing with your still functioning equipment.

Correct me if I'm wrong but I though you also had to shield something to protect it from an EMP.
Also if a bomb did go off, I doubt you'd want to be sitting around playing with your still functioning equipment.

I guess it's to disconnect devices from the power grid, as there could be a potentially destructive impulse coming through it.
Also, if a nuke explodes in low earth orbit, you'd create an EMP pulse that would affect big parts of the USA (yes, a single nuke), thus you wouldn't get any radioactive fallout or direct blastwave damage, but all electronic equipment would be of course destroyed if it's not shielded.

3rd February 2012
Last edited by ROBO_DONUT; 3rd February 2012 at 10:58PM.
Post #38

Correct me if I'm wrong but I though you also had to shield something to protect it from an EMP.
Also if a bomb did go off, I doubt you'd want to be sitting around playing with your still functioning equipment.

My guess is it's to protect from the secondary effects. You'd still need to shield the thing to protect it from the initial surge of EM radiation, but my guess is that there will be a short delay before you get the full effect from long transmission/signal lines, since electrons in metal conductors don't propagate as fast as EM waves in free space.
So, such a device would probably be mounted outside the shielded area, get triggered upon the initial EMP, and cut the connections to any transmission/power lines before any electrical surges hit. Transmission lines, I think, are the real problem because they cover so much physical area. Small circuits which aren't interconnected might be able to survive the initial effects.

According to Wikipedia the voltage from a nuclear detonation at an altitude of 400km will range from 25 to 50 kV per square meter over a very large area depending on bomb yield, altitude and your distance from detonation (your actually safer in terms of EMP closer to the detonation).
Assuming an area of 1sq cm this results in an induced voltage between 250 and 500V, more than enough to damage any sensitive electronics, so in order to completely protect something besides isolating it from the power line you'd also need to fully shield the device and provide full isolation (I.E optical) for any externally connected devices.
It's quite amazing at how much energy is produced in a nuclear explosion.